The ruling Communist Party is set to make the election of its elite Central Committee more competitive, which may cast further doubt over the political futures of several controversial candidates, including Ling Jihua, outgoing President Hu Jintao's former chief of staff, sources said.

Nine per cent of the nominees are expected to be eliminated during the primary elections for full membership when the congress Presidium announces the exact margin today, the sources familiar with the party's inner-workings said.

According to delegate Han Guiqing , president of the Agricultural Science Institute in Heilongjiang province, who was speaking on the sidelines of the party congress, 19 candidates were eliminated in the primary elections yesterday. The current Central Committee has 204 full members and 163 alternate members.

Competitive voting margins for the Central Committee at the previous two party congresses were 8.3 per cent in 2007 and a little over 5 per cent in 2002.

The 247-member Presidium will review the results of the primary elections and decide the candidates who will enter the formal vote tomorrow at the concluding session of the congress.

The sources said Ling, once one of China's most powerful men, was in danger of being edged out because of dissatisfaction among more than 2,200 party delegates about the alleged cover-up of a Ferrari crash that killed his son on Beijing's North Fourth Ring Road and seriously injured two young women. Although the accident occurred in March, the news emerged only in September. Despite persistent rumours Beijing has swept the scandal under the carpet, ignoring calls for an inquiry into Ling's role in the incident and its subsequent cover-up.

This is largely for fear of its potentially damaging impact on the once-in-a-decade leadership succession, especially in the wake of the downfall of ex-Politburo member Bo Xilai .

Although the prospects of Ling, once tipped as a contender for a seat at the top table of power, were dimmed when he was transferred to head the party's United Front Work Department, he has so far been exempt from formal investigation.

Party elders and Bo's supporters argue that Ling and Bo, who was expelled from the party and is facing criminal charges, should not be treated differently.

"Hu has been put in a delicate situation," one said.

Even if Hu uses his influence to help get Ling re-elected as the Central Committee member, Ling may still face internal investigation and have to deal with harsh criticism within the party. But if Hu decides not to help, it will leave an embarrassing impression that, after staying in power for a decade, he cannot protect his own protégé.

Analysts say the increased competitive margins in the primary elections of the Central Committee were a step in the right direction, but they also noted the formal election of the Central Committee tomorrow was unlikely to be competitive. More importantly, there is no sign that the party will extend the competitive elections to the Politburo and its Standing Committee.

Beijing-based analyst Chen Ziming said that without sufficient transparency and openness, the significance of such progress was not great.

"Although it is nominally competitive elections, they are held separately and behind closed doors among dozens of delegations and the results will not be made public before they are approved by the Presidium. What's more, no one knows how the Presidium works or whether it will overrule the primary election results," he said.

This article appeared in the South China Morning Post print edition as: